1. Field of the Invention
This invention relates to a retrofocus type wide angle lens, and more particularly to a retrofocus type wide angle lens of extremely small size having a large aperture.
2. Description of the Prior Art
Generally, in the retrofocus type lens, the distance between the negative lens system in the front lens component and the positive lens system in the rear lens component must be made long in order to obtain a sufficiently long back focus. Consequently, the overall length of the retrofocus type lens is generally great and the effective aperture of the negative lens of the front lens component is large. In practical use, the large aperture of the front lens component and the great overall length of the lens are inconvenient and undesirable.
In order to make the size of the lens compact, the distance from the front lens component to the rear lens component must be made as small as possible by increasing the refractive power of the negative lens in the front lens component. The increase in the refractive power of the negative lens in the front lens component, however, increases the degree of the various aberrations, particularly in the spherical aberration and comatic aberration. It is difficult to compensate for these aberrations particularly when the aperture of the lens is large.